|Publication number||US7573680 B1|
|Application number||US 11/364,127|
|Publication date||Aug 11, 2009|
|Filing date||Feb 28, 2006|
|Priority date||Nov 1, 2005|
|Publication number||11364127, 364127, US 7573680 B1, US 7573680B1, US-B1-7573680, US7573680 B1, US7573680B1|
|Original Assignee||Magnecomp Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (30), Referenced by (8), Classifications (4), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application claims priority from U.S. Provisional Patent Application No. 60/732,630 filed Nov. 1, 2005.
The present invention generally relates to techniques for operating a disk drive apparatus. More particularly, the present invention provides techniques for creating a vertical offset between hinge fingers in a disk drive suspension assembly in order to reduce track mis-registration error.
A hard disc drive (HDD) unit generally uses a spinning storage medium (e.g., a disk or platter) to store data. A read-write head is positioned in close proximity to the spinning storage medium by an HSA (Head Stack Assembly). Mounted on the HSA, a suspension assembly commonly includes a base plate, a load beam, and a flexure trace gimbal to which a slider is mounted. Alternatively the read-write head may be positioned by an integrated arm mounting assembly (known in the art as “Unimount”) including a mount plate adapted to a pivot bearing assembly at the proximal end and a load beam, flexure trace gimbal, and slider at the distal end. The slider supports the read-write head element. The load beam is generally composed of an actuator mounting region, a spring region, and a rigid region. The spring region gives the suspension a spring force or preload to counteract the aerodynamic lift force created by the spinning storage medium during reading or writing. A gimbal is mounted at the distal end of the load beam and supports the slider allowing the head to have pitch and roll movement in order to follow the irregularities of the disk surface.
Demand generally requires increased HDD storage capacity, which generally compels higher data track densities for the storage medium. Furthermore, the demand for faster rates of data seeking and accessing also leads to higher rotational speeds. A significant obstacle associated with increasing rotational speeds and storage capacity is often head positioning accuracy as the head flies above the spinning storage medium.
A significant obstacle to head positioning accuracy is disk flutter. Disk flutter is an aero-elastic instability induced by the coupling of the spinning storage medium and the air surrounding the media resulting in disk vibration modes. These flow induced vibrations can physically cause an off-track misalignment of the head to the desired track resulting in failure to access or write data on the track center. Problems associated with disk flutter become more intolerable with higher track densities and disk rotation speeds.
The desirability of introducing a vertical offset in the hinges in a head suspension is described in U.S. patent application Ser. Nos. 11/119,363 and 11/119,364, both of which were filed on Apr. 29, 2005, both of which are assigned to the assignee of the present application, and both of which are herein incorporated by reference. The present invention provides structures and techniques for producing head suspension assemblies which incorporate the desired vertical offset.
The present invention provides methods and structures for producing a vertical offset within the hinges of a head suspension assembly, so that the assembly can compensate for track mis-registration errors caused by imperfections in the disk surface, flow induced vibrations, and other sources of mis-registration. Merely by way of example, the present invention is implemented using such method and apparatus with a vertical offset between at least two spring extensions (or hinges) coupling an actuator mounting region to a rigid region of a load beam. The vertical offset between spring extensions (or hinges) results in an effective hinge predisposed to move in a predetermined direction.
In the present application, the vertical offset is achieved by etching one or more portions of the assembly in which at least one of a spring extension, the load beam and the mount beam comprise a laminate. There are several different embodiments. In one embodiment of a suspension assembly for a hard disk drive, the suspension assembly includes a load beam, a mount plate, first and second spring extensions extending between the load beam and the mount plate, a vertical offset between the first and second spring extensions, and at least one etched area on at least one of the load beam and mount plate, the etched area facilitating the vertical offset.
Considering additional possible features, the mount plate and load beam may include a laminate material. The laminate material may have at least three layers. In one embodiment, the laminate material has two layers of stainless steel, and a layer of polyimide disposed between the two layers of stainless steel. A corner of the mount plate and a corresponding corner of the load beam may be etched. In another embodiment, to form two adjacent cantilevers vertically spaced from one another, the mount plate may be made of a laminate material, and on one side of one end of the mount plate, a top portion of the material can be etched off, and a bottom portion of the material on the other side can be etched off, to form the cantilevers. The mount plate may optionally be pre-split through the layers of the composite prior to being etched.
A spring extension may be formed of a laminate material, with the spring extension being etched on either end to form a raised center portion. There may be a gap between the load beam and the mount plate, the raised center portion spanning the gap. The assembly may include two spring extensions, a first spring extension being etched to form a raised center portion and a second spring extension that is relatively flat compared to the first spring extension.
In another embodiment, the mount plate has a first mesa and the load beam has a second mesa, the first and second mesas being substantially adjacent one to the other, with a spring extension extending from the first mesa to the second mesa. A second spring extension extends from a non-mesa portion of the mount plate to a non-mesa portion of the load beam.
In another embodiment, the mount plate may include a first recess and the load beam may include a second recess, with a spring arm extending from the first recess to the second recess.
Considering another aspect of the invention, a suspension assembly for a hard disk drive has a load beam, a mount plate, first and second spring extensions extending between the load beam and the mount plate, a vertical offset between the first and second spring extensions, and means for facilitating the vertical offset.
In another aspect of the invention, a method of achieving a vertical offset between a first and a second spring extension on a suspension assembly for a disk drive may include the steps of etching portions of the load beam and mount plates and extending at least one of said first and second spring extensions from an etched portion of the load beam to an etched portion of the mount plate. The method may optionally include the step of etching a mesa on at least one of the load beam and the mount plate. The etching step may include etching through at least one layer of a laminate material. The method may further include providing means for passive damping. The method may also include using a first chemical to etch a first layer of at least one of the load beam and the mount plate, and a second chemical is used to etch a second layer of at least one of the load beam and the mount plate. For example, in one example approach, the first layer is stainless steel and is etched with ferric chloride, and the second layer is polyimide and is etched with sodium hydroxide.
In another embodiment, a suspension assembly for a hard disk drive has a load beam, a mount plate, and first and second spring extensions extending between the load beam and the mount plate. At least one of the spring extensions is made with a composite material. There is a vertical offset between the first and second spring extensions, with at least one etched area on the composite material. The etched area facilitates the vertical offset.
The foregoing is but a brief summary of the invention, and further aspects of the invention will be found in the following Detailed Description, in the Drawings, and in the Claims. Consequently, the invention is not limited by this Summary.
Techniques for operating a disk drive apparatus are provided. More particularly, the present invention provides a method and apparatus for reading and writing information onto a hard disk drive that compensate for flow induced vibrations.
Disk 101, commonly called a platter, rotates about a fixed axis (or spindle) from about 5,000 rpm up to about 15,000 rpm depending upon the embodiment. Disk 101 stores information and thus often includes a magnetic medium such as ferromagnetic material, but it can also include optical materials, common coated on surfaces of the disk, which become active regions for storing digital bit information. The aggregate storage capacity of disk 101 will vary with track density and disk diameter. Disk 101 stores information in tracks which can be in a range of about 50,000 tracks per inch (TPI) to about 200,000 TPI, or more. The diameter of disk 101 can be 5.12 inches (e.g., for a 5.25 inch drive), 3.74 inches (e.g., for a 3.5 inch drive), or less than 2.5 inches, or even less than 1.8 or 1.0 inch.
Suspension assembly 105, which overlies (or underlies) a surface of disk 101, operates and controls a slider coupled to a read/write head (not shown). Flexure trace gimbal assembly 109 is attached to suspension assembly 105 which in turn connected to actuator arm 103. Actuator arm 103 is connected to a voice coil motor or VCM, which move suspension assembly 105 about a pivot point in an annular manner. The VCM can move at frequencies from DC up to about 1 kHz. Preferably, for higher track density, e.g., 200,000 TPI, the control bandwidth can approach 5 kHz, but can also be greater in certain embodiments.
Broadly speaking, the present invention relates, but is not limited, to method of providing a vertical offset between at least two spring extensions (or hinges) coupling an actuator mounting portion to a rigid support member (or load beam). The vertical offset between spring extensions (or hinges) results in an effective hinge predisposed to move in a predetermined direction in order to reduce track mis-registration errors. The various embodiments of the present invention generally accomplish this vertical offset by etching one or more portions of at least one component of the assembly.
Considering one aspect of the present invention, layers of a laminate material may be etched away in order to facilitate a vertical offset in two or more spring extensions connecting the load beam to the mount plate. One approach starts with a three-layer (stainless steel-polyimide-stainless steel) laminate material to make the mount plate, the hinges and/or the load beam of the suspension. The three-layer component (e.g. the mount plate, the hinges or the load beam) is then etched through the first two layers to expose the bottom stainless steel layer. The etching is confined only to certain areas of the component and in some cases the etching needs to be done both on the top and bottom surfaces of the component.
In one method of this etching technique, a two-step approach is taken. The stainless steel (which may be foil) is etched with ferric chloride, for example, or with another suitable etching compound known in the art. The polyimide is etched with sodium hydroxide, for example, or another compound suitable for etching polyimide. Etching techniques are well-known in the art, and can be outsourced to any of a number of etching companies.
After etching is complete, the components are welded together in a conventional manner. It should be noted that, in conjunction with the etching techniques and some of the embodiments discussed below, the number of welds may be reduced as compared to traditional hinge structures.
Considering now specific examples of the invention, three example configurations according to this approach are illustrated in
In the embodiment of
It is noted that, as an alternative, a transverse split made before the etching process can help in separating the two limbs of the hinge. That is, a lengthwise split may be stamped into the laminate material prior to etching, defining the lengthwise boundary between what will become the two portions 242, 244 of the hinge. This split may help to reduce any surplus webbing that might otherwise appear after the etching process is finished. Also, as an alternative, the load beam might also be made of laminate and etched differentially in the same manner as the mount plate, but in a complementing fashion, then welded.
As another alternative, the mount plate, hinges and the load beam could be ‘sculpted’ from a single, three-layered laminate sheet. In this approach, etching is done in the middle area of the sheet to form the hinges. The load beam and the mount plate are left unetched on either ends of the hinge area.
Considering further embodiments, in
Among the advantages of the etched laminate embodiments of
Composite structures may also be incorporated into known designs, such as those illustrated in
Considering another approach,
A further advantage of the approach of
In summary, referring to
As to materials used to form the various structures discussed herein, it is noted that the various members disclosed herein can be made of materials known in the art. In many of the embodiments, one or more components will be made of a composite laminate material. Some of these embodiments include a visco-elastic layer such as polyimide to assist in structural damping during operation of the hard drive. Further structural aspects are discussed in the previously-noted U.S. patent application Ser. Nos. 11/119,363 and 11/119,364, both of which were filed on Apr. 29, 2005, and which are incorporated by reference herein.
It should be noted that, in the following claims, the term “spring extension” can mean a stand-alone plate as show in
As a further matter of terminology, the meaning of “mount plate” as used in the claims is expanded to also mean “base plate,” so that a claim in which the term “mount plate” appears also includes alternative embodiments in which a base plate is used rather than a mount plate.
It will be appreciated that the term “present invention” as used herein should not be construed to mean that only a single invention having a single essential element or group of elements is presented. Similarly, it will also be appreciated that the term “present invention” encompasses a number of separate innovations which can each be considered separate inventions. Although the present invention has thus been described in detail with regard to the preferred embodiments and drawings thereof, it should be apparent to those skilled in the art that various adaptations and modifications of the present invention may be accomplished without departing from the spirit and the scope of the invention. Accordingly, it is to be understood that the detailed description and the accompanying drawings as set forth hereinabove are not intended to limit the breadth of the present invention, which should be inferred only from the following claims and their appropriately construed legal equivalents.
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|Feb 28, 2006||AS||Assignment|
Owner name: MAGNECOMP CORPORATION, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KULANGARA, SIVADASAN;REEL/FRAME:017639/0191
Effective date: 20060221
|Oct 13, 2009||CC||Certificate of correction|
|Feb 1, 2013||FPAY||Fee payment|
Year of fee payment: 4